Classical Conditioning 1 PDF

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Lecture 2Part 1 : basic concepts & role of cerebellumTypes of conditioning Operant conditioning - Associate voluntary behaviour and consequence Classical conditioning - Associate involuntary response and stimulusBasic concepts of classical conditioning - Before conditioning - Unconditioned stimu...

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Classical Conditioning Lecture 2 Part 1 : basic concepts & role of cerebellum Types of conditioning Operant conditioning - Associate voluntary behaviour and consequence Classical conditioning - Associate involuntary response and stimulus Basic concepts of classical conditioning • Before conditioning - Unconditioned stimuli (UCS), unconditional response (UCR) - Neutral stimuli do not evoke response • Conditioning - Pairing of neutral stimulus + unconditioned stimulus -> neutral stimulus becomes con • After conditioning - Conditioned stimulus (CS) evokes conditioned response (CR) Organisation of cerebellar cortex

ditioned stimulus

Modifying synaptic input Mossy fibers - carry sensorimotor information MFs can excite Purkinje cells through Parallel fibers MFs can inhibit PCs via molecular layer interneurones (MLI) Strength of PF and MLI inputs to PCs modulated through syn Plasticity regulated through Climbing fiber (CF) inputs

Eye-blink conditioning (form of CC) Paradigm : tone sounded prior to air-puff. Animals learns to associate tone with air-puff and • Before conditioning : CS -> no CR. US -> UR - PCs inhibit eye closure - Tone (CS) is encoded via MF input but has no effect on PC activity - Air-puff (UCS) results in CF response and results in blink • During conditioning : CS + US -> UR - Tone + air puff pairing, associative learning - Weakening of tone evoked PF-PC input - Strengthening of MLI-pc input • After conditioning : CS -> CR - Net result = reduction of PC firing - Leads to disinhibition of circuitry for eye closure Cerebellar pathways

naptic plasticity

d closes it's eye upon hearing tone alone

Associative learning in eye-blink conditioning -

Less inhibition from PCs onto Strong influence from MLI fr Causes disinhibition of PC to

Weakening of associations • Associative learning : association and strengthening • Behavioural extinction : associations not reinforced are weakened - Repeated activation of CS alone leads to loss of CR - Originates from new CS - no US memory that competes with original memory

o motor nucleus rom PFs to PCs motor nucleus...